The present invention relates to a mechanism for opening and closing a first body with respect to a second body which is pivotally connected to the first body.
There has been known a device that include a lower body and an upper body pivotably mounted to the lower body via a hinge such as an image forming apparatus, the upper body of which accommodates an image scanner while the lower body a printer that forms images, on a recording medium, read by the imaging scanner from an original.
In such an image forming apparatus, a spring member is provided for biasing the upper body to pivot upon a hinge to the open position thereof. The strength of the spring member is so adjusted that the upper body manually swung by a user to the arbitrary open position thereof does not swing back toward or fall down onto the lower body due to its own weight but remains stationary there even if a user released its hand therefrom. Thus, a user can locate the upper body at any arbitrary open position with respect to the lower body.
For closing, a user manually pushes down the upper body onto the lower body. At this time, the upper body tends to apply undesirable large impact onto the lower body due to the own weight thereof. Such large impact can be prevented by increasing the strength of the spring member. However, if the strength of the spring member is increased for that purpose, the biasing force thereof becomes too large for keeping the upper body stationary at a desired open position, and the upper body springs up to a fully opened position thereof each time.
Thus, a user has been forced to pay attention every time to softly place the upper body on the lower body, which has been considerably troublesome for a user.
It is therefore an object of the invention to provide an opening and closing mechanism for a hinged pair of bodies capable of smoothly and softly closing them without a user paying attention thereto.
According to an aspect of the invention, there is provided an opening and closing mechanism that includes first and second bodies and a biasing mechanism. The first body is pivoted to the second body so that it is movable between open and close positions with respect to the second body. The biasing mechanism biases the first body to move it toward the open position thereof. The biasing mechanism includes an resilient member and exerts a first biasing force on the first body by linearly stretching the resilient member. When the first body is in the vicinity of the second body, the biasing mechanism further exerts a second biasing force on the first body by bending the linearly stretched resilient member.
By the opening and closing mechanism arranged as above, a user can smoothly move the first body from the open position toward the close position and also close the mechanism softly since the biasing mechanism increases the biasing force by bending the resilient member only when the first body is in the vicinity of the second body.
The opening and closing mechanism further includes a link-arm member connected between the first and second bodies in such a fashion that the end of the link-arm member coupled to the second body moves relative to the second body as the first body moves. The resilient member is arranged to be linearly stretched/contracted upon movement of the link-arm member, and hence upon movement of the first body. Thus, the first biasing force generated by the spring member can be varied in accordance with the location of the first body.
The link-arm member is provided with an contact portion that contacts and bends the resilient member at a side thereof when the first body is in the vicinity of the second body so that the link-arm member is pushed back by the side of the resilient member and thereby biases the first body towards the open position.
The contact portion is, for example, a protrusion formed on the link-arm member so that the more the first body approaches the close position thereof in the vicinity of the second body, the more the bending amount of the resilient member increases.
In order to increase the bending amount of the resilient member, the mechanism may further include a supporting member that is arranged to contact the resilient member from the opposite side when the protrusion contacts the resilient member.
The link-arm member may further have a portion of U-shaped section and the contact portion may be disposed therein such that it comes in contact with the resilient member received in the U-shaped section. By such an arrangement, the resilient member is prevented from sliding off from the contact portion and the generation of the second biasing force is ensured.
In some cases, the mechanism is arranged such that the first body is disposed on the second body. In such a case, the strength of the resilient member may be so adjusted that the first biasing force prevents the first body from falling down towards the second body due to its own weight and keeps the first body at an arbitrary position between the open and close position thereof.